Crystal Growth from a Supersaturated Vapor

Because the adatoms diffuse relatively rapidly along the surface and the ledges to the kinks, many more atoms reach the kinks by these routes than by direct impingement from the vapor. Note the close similarity between this crystal growth process on a vicinal surface and the climb of dislocations depicted in Fig. 11.2. 

In Exercise 12.2 it is shown that the growth velocity can be expressed in the form 

An initially singular and atomically flat surface advances only if ledges, possessing kinks, are nucleated and formed on the surface. This can occur if adatoms cluster together on the surface and nucleate new ledges at small pillbox-shaped clusters of adatoms as indicated in Fig. 12.1. The free energy to form such a cluster 

General Crystal Surfaces. General surfaces possess a high density of sites where atoms from the vapor can be incorporated in the crystal and are therefore expected 

There is a body of experimental evidence generally supporting the models above for growth at the different types of surfaces [1]. 

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